The present invention relates in general to dryer appliances for clothes and other washable products. It finds particular, but not exclusive, utility in an energy efficient clothes dryer of the type utilizing a rotatable tumbling drum and heat pump for circulating a flow of heated air through the drum.
National energy policy in the United States now calls for gradually phasing out conventional electrical appliances which are energy inefficient in favor of appliances which are energy efficient. The urgency underlying this policy is readily apparent, since about 75 percent of the energy consumed in an ordinary household is used by various electrical appliances including clothes dryers. Appliance buyers are now learning to look for energy efficiency, as well as price, in making their appliance selections.
Conventional electric resistor heated clothes dryers, widely used in homes and laundromats, do an acceptable job of drying but are not energy efficient. Such dryers operate with high power consumption which typically may be on the order of 4000 to 5500 watts. They normally require a 220 volt power supply which often must be specially installed at considerable expense. They also require installation of an air vent duct to the outside, resulting in further expense.
As an alternative, and also as a supplement, to an electrical resistor heat source, it has been known heretofore to use waste heat from a heat pump condenser in a clothes dryer or other drying apparatus. These prior arrangements are for the most part complex in structure and operation, or cumbersome, or crude, and are not well suited for efficient layout within the confines of a household clothes dryer cabinet.